Irregular verbs are a special type of verbs which do not follow the usual pattern when they are used in past tenses. These verbs don't get usual -ed in simple past and past participle, but form other types of verbs. In English there are about 370 irregular verbs and the easiest way to learn all the forms is to learn them in groups.
A lot of verbs are the same in all three forms for example bet, burst, hurt, put and others. That means that we can learn just the infinitive and use it in all three forms for example. In present: I always bet on my team. In past simple: I bet on my team a while ago. Or we can also use it as past participle for example: I had bet on my team, before I changed my mind.
The other group of verbs is really big. A lot of verbs have the exact same simple past and past participle like: bring (brought, brought), feel (felt, felt), get (got, got), sell (sold, sold) and so one.
There are also some rare examples of the verbs with the same infinitive and simple past, but different past participle, like beat (beat, beaten) and some where infinitive and past participle are the same like become (became, become), come(came, come) and run (ran, run).
And of course the last group where none of the forms match, verbs like be (was/were, been), eat (ate, eaten), fall (fell, fallen) and others. Once you master all 3 forms and of course translation to your native language.
To learn or test English irregular verbs try this exercises Learn English Irregular Verbs Online http://www.irregular-verbs.info/.